Triplet supercurrent in ferromagnetic Josephson junctions by spin injection

TL;DR

This paper demonstrates that spin injection into superconducting leads can significantly enhance and control long-range triplet supercurrents in ferromagnetic Josephson junctions, enabling tunable superconducting transport.

Contribution

It introduces a method to generate and manipulate long-range triplet supercurrents via spin injection and exchange interaction in superconductor-ferromagnet junctions.

Findings

Spin injection enhances Josephson current in ferromagnetic junctions.

Long-range supercurrent is carried by triplet Cooper pairs.

The supercurrent can be controlled by the polarization angles.

Abstract

We show that injecting nonequilibrium spins into the superconducting leads strongly enhances the stationary Josephson current through a superconductor-ferromagnet-superconductor junction. The resulting long-range super-current through a ferromagnet is carried by triplet Cooper pairs that are formed in s-wave superconductors by the combined effects of spin injection and exchange interaction. We quantify the exchange interaction in terms of Landau Fermi-liquid factors. The magnitude and direction of the long-range Josephson current can be manipulated by varying the angles of the injected polarizations with respect to the magnetization in the ferromagnet.